If slaughterhouses had glass walls, everyone would be vegetarian.
—Paul and Linda McCartney
onomatopoeia
A figure of speech in which words are used to imitate sounds. Examples of onomatopoeic words are buzz, hiss, zing, clippety-clop, and tick-tock. Keats's "Ode to a Nightingale" not only uses onomatopoeia, but calls our attention to it: